Some electronic products, such as industrial or measuring instruments, have calibration certificates. These record a series of test runs and the measured result, along with details about the product, such as serial and model numbers. For example a flowmeter often has a flow calibration certificate recording a series of test runs and the measured result. Or a weigh scale will have a series of test weights applied and the measured result and error recorded. Traditionally such certificates of calibration are printed on paper and supplied with the electronic product. In many situations, the end user loses the calibration certificate, or it never reaches the required person, for example because it is being lost during commissioning. Although normally the manufacturer of the instrument stores copies of the original document, it is not always straightforward for the end user to get a duplicate. In some situations quality processes, inspections or audits will require this original calibration certificate or subsequent re-calibration to be available.
One possible way to ensure availability of required calibration certificates is to store an image or electronic record of the calibration certificate inside an electronic memory within the electronic product. Hereby an external computing device acts as a means of uploading, viewing, distributing and printing the internally stored calibration certificate. The drawback with this method is that for a typical one page certificate its size, would be too large for the very low capacity of electronic storage available in electronic products. Electronic instruments like industrial or measurement instruments typically have a very limited amount of non-volatile storage, about one to two k-bytes only. Whilst well know compression algorithms exist, such as jpeg or portable document formats such as pdf, for a typical one page calibration certificate its size, even if compressed, would be around 18 k bytes. This is still far too large for storage available in electronic instruments such as industrial or measurement instruments.